1. Field of the Invention
The present invention generally relates to the field of the packaging technology and concerns a method and a device for packaging of flat objects with the aid of a packaging material that is supplied as a quasi-endless web and, more particularly, toward such a method and device wherein the packaging material is a web of a weldable plastic film or sheet material supplied from a supply reel.
2. Description of Related Art
A known method for continuously packaging individual printing products or small batches of printing products using a web of a plastic film or sheet material supplied from a reel comprises guiding a product stream, in which the products to be packaged are oriented parallel to the conveying direction and are conveyed behind each other and spaced from one another, between two webs of the packaging material, or joining the product stream with one web and then wrapping the web round the products or round the stream respectively. Then the web or webs of film material are sealed parallel to the conveying direction, and they are sealed and separated in the gaps between the products, i.e. transverse to the conveying direction. Such a method and a device for carrying out the method are described in the publication EP-1188670.
Packaging methods as mentioned above reach their limits regarding performance in produced packages per time unit relatively soon, because the products are conveyed parallel to the conveying direction and behind each other. For high performance, particularly in the case of products being relatively long in conveying direction, the above-mentioned methods lead to conveying speeds that are not easily achieved.
Higher piece performances at easily achieved conveying speeds are known to be possible if the products are conveyed in a conveying stream in which they are not aligned parallel to the conveying direction but rather essentially transverse to the conveying direction. The publication EP-0588764 (Grapha Holding AG) describes a device that is apparently suitable for packaging products being supplied in such a manner. The device comprises a processing drum of the kind used for inserting supplements into printing products or into folded sheets of packaging material. The plastic web is drawn from a supply point at the drum periphery in a zig-zag motion into the compartments of the drum, which are arranged in succession around the circumference of the drum. The bags thus formed are then charged with products, separated, and sealed, and the completely packaged products are removed from the drum compartments.
In the publication DE-3838985 (MAN) an equivalent device for batch-wise operation is described in more detail. With the aid of this device the plastic film web supplied from the supply reel is spread out in a zig-zag, creating a predetermined number of V-shaped bags that are open along three edges and in which the products to be packaged are positioned. Then the bags are separated, closed around the product within, sealed along the three open edges, and discharged from the device. Not until then another given number of bags are formed and the procedure is repeated. For each bag to be fashioned in one batch, an essentially identical device-part is provided and all device-parts are operated simultaneously.
No proposals as to how the described devices, in particular the continuously operating devices, can be adapted to varying formats of the objects to be packaged are found in any of the aforementioned publications. Therefore, it is the object of the invention to tackle this very task. As long as this object is not achieved, either elaborate adjustments of the device are required as soon as objects with a differing format are to be packaged, or a separate device is necessary for each format, or else products with differing formats are packaged using the same package format, which leads to insufficiently adjusted packaging and presents a waste of packaging material, particularly in the case of large numbers of packages to be produced.